Fuse plug



J. WEBER FUSE PLUG oct. 12,'1937.

Filed March 8, 1935 J l 40 38 3f 33 3720 Patented Oct. 12, 1937 UNITED STATES PATENT OFFICE Alpine Electric Corporation,

Schenectady,

N. Y., a corporation of New York Application March 8, 1935, Serial No. 10,102

9 Claims.

The present invention relates to fuse plugs and has as its general purpose to provide fuse plugs wherein the component parts may be cheaply made, readily assembled and securely associated.

In order that the invention may be fully understood, I shall describe it with reference to the specic embodiments shown, by way of example, in the accompanying drawing. In the drawing:

Figure l is an elevation partly broken away of one practical embodiment of the invention;

Figure 2 is a plan view of the embodiment shown in Figure l;

Figure 3 is a section substantially on line 3 3 of Figure 2;

Figure 4 is a plan view of the same embodiment with a cap portion removed;

Figure 5 is a bottom plan view of the said cap portion; and Y Figure 6 is a detail in perspective.

Referring to the drawing, reference numeral 20 designates a body of insulating material such as porcelain, the body having a cavity 2| opening at the outer end of the body, the inner end of the body being apertured to receive a contact 22.

The body has a main substantially cylindrical portion 23, as here shown, and a frusto-pyramidal extremity 25 between which and portion 23 is an annular shoulder 26. The body is loosely embraced by a threaded shell 2'1 which, at its inner end, has an annular ilange 28 engaged with shoulder 26. A fusible element 29 has its inner end soldered to contact 22, its outer end being bent and disposed in a groove 30 at the outer end ofthe body With its extremity soldered to the shell. A cap 3| is screw-engaged with the outer end of shell 21, the inner threaded portion of the shell being engageable with the threads of the ordinary socket so as torconnect the fusible element into a circuit in the usual manner.

The walls of the cavity at its outer end are recessed to form an annular seat 32 on which rests the marginal portion of a closure disc 33 of mica or the like. Opposite groove 30, as here shown, the outer wall or rim 2S of the body is provided with a. groove 34 and with an axially extending slot 35 at one end of the groove.

Cap 3| is preferably made of a phenolic condensation product and has a top wall 35 from which a threaded skirt portion depends. Centrally, wall 36 is provided with an opening 3'| and the inner edge of this opening is rimmed by an annular rib 38 which overlies seat 32. Outwardly of rib 38, the underside of wall 36 is provided with a circular series of teeth 39, which teeth are sloped in a counter-clockwise direction (Cl. 20o-130) as seen from the bottom of the cap. Teeth 39 are positioned to overlie the outer rim of the body outside of seat 32.

A small metal strip 40 is bent to provide an end 15| which is engaged in slot 35 with the other por- 5 tion 42 of the strip projecting into the recess 34. When the cap 3| is screwed on the shell 2l, portion 42 acts as a depressible spring tooth for cooperation with teeth 39 so as to prevent releasing rotation of the cap relative to the body 20. The 10 tapered portion 25 of the body, which is of substantially truncated pyramidal form, is followed in contour by the inner edge of ilange 28 so as to prevent relative rotation of the shell and body.

Portion 42 of strip 40 is of such a length as 15 not to project beyond the connes of recess 34 and for this reason cannot be engaged between the tooth 39 and the rim of the body.

With the fusible element 29 soldered in position as shown in Figure 3, assembly is completed 20 by placing the disc 33 on its seat and then screwing the cap 3| on the outer end of shell 2l. As this operation progresses the rib 38 engages the disc 33 and bears it against its seat 32, the ilange 28 of the shell taking the reaction of the cap so 25 that the body 20 is securely engaged between the flange 28 and rib 38 and disc 33 is clamped against its seat. The cap in its final position is engaged by the tooth 42 and can not be reversely turned relative to shell 2'| since the latter is held 30 against rotation relative to body 20 due to the engagement of the inner edge of ange 28 with the non-round boss 25,

Gases may escape from the cavity 2| through the recess 30 to the space between the shell and 35 the body, this space constituting a relatively confined gas escape passage due to the cylindrical, rather than tapered, form of the body.

It will be understood that variations may be made in details and arrangement from what has 40 been disclosed herein without departure from the invention, and accordingly I do not limit myself except as in the following claims.

I claim:-

1. A fuse plug comprising a body of insulating 45 material, said body having inner and outer ends and having a cavity with an opening at said outer end, a fusible element in said cavity, a threaded shell embracing said body in non-rotatable relation thereto, a closure cap threaded on the outer end of said shell, said cap having a circular series of teeth overlying the outer end of said body, said outer end of said body having a recess therein, and a depressible metal tooth conned wholly to said recess in longitudinal extent and engaging one oi said series of teeth to lock said cap against rotation in the releasing direction.

2. A fuse plug comprising a body of insulating material, said body having inner and outer ends and having a cavity with an opening at said outer end, a fusible element in said cavity, a threaded shell embracing said bodyin non-rotatable Vrelation thereto, a closure cap threaded on the outer end of said shell, said cap having a circular series of teeth overlying the outer end of said body, said outer end of said body having a recess therein and a narrow slot in the bottom of said recess, a spring strip having one end engaged in said slot and the other end bent into engagement behind one of the teeth of said series of teeth to lock'said cap against rotation in the releasing direction, the bent portion of said tooth being coniined wholly to said recess. f

3. A fuse plug comprising a body of insulating material, said body having inner and outer ends and havingV a c-avity with an opening at said outer end, the walls of the cavity at said opening being recessed to provide an annular seat spaced from the outerend of said opening, a closure disc having a marginal portion disposed on said seat, a cap member screw engaged with the outer end of said body and having an opening registering with said cavity, the underside of the cap memberV 'having an annular'rib Arimming the cap member opening and'engaging said disc to hold it on said seat, a series of teeth on the underside of said cap surrounding said rib, saidV outer end of said body having a recess therein, and a depressible metal tooth conned wholly to said recess in longitudinal extent and engaging one of said series of teeth to lock said cap against rotation in the releasing direction.

4. A fuse plug comprising a body ofinsulating material, said'body having inner and outer ends and having a cavity with an opening at said outer end, a contact externally exposed at the inner end of said body and extending into the inner end of said cavity, an externally threaded conductive shell surrounding said body, said body being freely insertable in said shell to assemble the two, cooperating abutment portions on the shell and body for limiting movement of s-aid shell toward Vthe outer end of said body, a disc closing the outer end of said cavity and having a marginal portion overlying lthe outer end of the body, a fusible strip in said cavity connectingY said contact and the outer end of said shell, the outer end of said strip being passed beneath theV marginal portion of said disc, and a centrally apertured cap having an internally threaded skirt screwed on the outer end portion of said shellV and having an inner marginal portion overlying the marginal portion of s-aid disc, said cap when screwed on said body serving to engage said marginal portion of said disc and to draw said abutment portionsY intoY engagement, the inner end portionofsaid shell being engageable with the threads of the usual socket.V

5. A fuse plug comprising a body of insulating material, said body having inner and outer ends and having a cavity with an opening at said outer end, a contact externally exposed at the inner end oi said body and extending into the inner end of said cavity, an externally threaded conductive shell surrounding said body, said body being freely insertable in Vsaid shell to assemble the two, cooperating abutment portions Yon the shell and body for limiting movement of said Vshell toward the outer end of said body, a disc closing the outer endo said cavity and having a marginal portion portion overlying the marginal portion of said disc, said cap when screwed on said body serving toengage said marginal portion of said disc and to draw said abutment portions into engagement, the inner end portion oi said shell being engageable vwith'the threads of the usual socket, and means locking said cap against unscrewing.

6. A'fuse plug comprising a body of insulating material, said body having inner and outer ends and having a cavity with an opening at sai-d outer end, a contact externally exposed at the inner end of said body and extending into the inner end of said cavity, an externally threaded conductive shell surrounding said body and having a flange adapted to bear against the inner end of said body, said body being freely insertable in said shell to assemble the two, a disc closing the Vouter end of said cavity and having a marginal portion overlying the outer end of said body, a fusible strip in said cavity connecting said contact and shell, the outer end of said strip being passed beneath the marginal portion of said disc, anda centrallyY apertured cap having an internally threaded skirt screwed on the outer end portion of said shell and having an inner marginalY portion overlying the marginal portion of said disc, said cap when screwed on said body serving to engage said marginal portion of said disc and to draw said flange against the inner end of said body, the inner end portion oi said shell being engageable with the Ythreads of the usual socket.

'7. A fuse plug comprising a body of insulating material, said body having inner and outer ends and having a cavity with an opening at said outer end, a contact externally exposed at the inner end of said body and extending into the inner 'Vend of said cavity, an externally threaded conductive Vshell surrounding said body and havingV a flange adapted to bear against the inner end of said body,

-said body being freely insertable in said shell to assemble the two, a disc closing the outer end of said cavityand having a marginal portion overlying the outer end of said body, a fusible strip in said cavity connecting said contact and shell, the outer end oi said strip being passed beneath the marginal portion of said disc, a centrally apertured cap having an internally threaded skirt screwed on the outer end portion of said shell and having an inner marginal portion overlying the marginal portion of said disc, said cap when screwed on said body serving to engage said marginal portion of said disc and to draw said flange against the inner end of said body, the inner end portion'of said shell beingy engageable'with the threads of the usual socket, and means locking said cap against unscrewing.

8. A fuse plug comprising a body of insulating materiaL'said body having inner and outer ends and having a cavity with an opening at said outer end, said body having a non-round boss at its inner end, a contact externally exposed at the end of said boss and extending into the inner end of said cavity, an externallythreaded conductive shell'surrounding said body and having a flange boss to prevent rotation of said shell relative to said body, a disc closing the outer end of said cavity and having a marginal portion overlying the outer end of said body, a fusible strip in said cavity connecting said contact and shell, the outer end of said strip being passed beneath the marginal portion oi said disc, and a centrally apertured cap having an internally threaded skirt screwed on the outer end portion of said shell and having an inner marginal portion overlying the marginal portion of said disc, said cap when screwed on said body serving to engage said marginal portion of said disc and to draw said ange against the inner end of said body, the inner end portion of said shell being engageable With the threads of the usual socket.

9. A fuse plug comprising a body of insulating material, said body having inner and outer ends and having a cavity with an opening at said outer end, said body having a non-round boss at its inner end, a contact externally disposed at the end of said boss and extending into the inner end of said cavity, an externally threaded conductive shell surrounding said body and having a flange adapted to bear against the inner end of said body, said flange having an inner edge initially congured to cooperate with said boss to prevent rotation of said shell relative to said body, said body being freely insertable in said shell to assemble the two, a disc closing the outer end of said cavity and having a marginal portion overlying the outer end of said body, a fusible strip in said cavity connecting said contact and shell, the outer end of said strip being passed between the marginal portion of said disc, a centrally apertured cap having an internally threaded skirt screwed on the outer end portion of said shell and having an inner marginal portion overlying the marginal portion of said disc, said cap when screwed on said body serving to engage said Inarginal portion of said disc and to draw said iiange against the inner end of said body, the inner end portion of said shell being engageable with the threads of the usual socket, and means locking said cap against unscrewing.

JOHN WEBER. 

